Calculus Examples

$y = {(\ln (x))}^{\cos (x)}$

Step 1

Use the properties of logarithms to simplify the differentiation.

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Step 1.1

Rewrite ${(\ln (x))}^{\cos (x)}$ as $e^{\ln ({(\ln (x))}^{\cos (x)})}$ .

$\frac{d}{d x} [e^{\ln ({(\ln (x))}^{\cos (x)})}]$

Step 1.2

Expand $\ln ({(\ln (x))}^{\cos (x)})$ by moving $\cos (x)$ outside the logarithm.

$\frac{d}{d x} [e^{\cos (x) \ln (\ln (x))}]$

Step 2

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = e^{x}$ and $g (x) = \cos (x) \ln (\ln (x))$ .

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Step 2.1

To apply the Chain Rule, set $u_{1}$ as $\cos (x) \ln (\ln (x))$ .

$\frac{d}{d u_{1}} [e^{u_{1}}] \frac{d}{d x} [\cos (x) \ln (\ln (x))]$

Step 2.2

Differentiate using the Exponential Rule which states that $\frac{d}{d u_{1}} [a^{u_{1}}]$ is $a^{u_{1}} \ln (a)$ where $a$ = $e$ .

$e^{u_{1}} \frac{d}{d x} [\cos (x) \ln (\ln (x))]$

Step 2.3

Replace all occurrences of $u_{1}$ with $\cos (x) \ln (\ln (x))$ .

$e^{\cos (x) \ln (\ln (x))} \frac{d}{d x} [\cos (x) \ln (\ln (x))]$

Step 3

Differentiate using the Product Rule which states that $\frac{d}{d x} [f (x) g (x)]$ is $f (x) \frac{d}{d x} [g (x)] + g (x) \frac{d}{d x} [f (x)]$ where $f (x) = \cos (x)$ and $g (x) = \ln (\ln (x))$ .

$e^{\cos (x) \ln (\ln (x))} (\cos (x) \frac{d}{d x} [\ln (\ln (x))] + \ln (\ln (x)) \frac{d}{d x} [\cos (x)])$

Step 4

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = \ln (x)$ and $g (x) = \ln (x)$ .

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Step 4.1

To apply the Chain Rule, set $u_{2}$ as $\ln (x)$ .

$e^{\cos (x) \ln (\ln (x))} (\cos (x) (\frac{d}{d u_{2}} [\ln (u_{2})] \frac{d}{d x} [\ln (x)]) + \ln (\ln (x)) \frac{d}{d x} [\cos (x)])$

Step 4.2

The derivative of $\ln (u_{2})$ with respect to $u_{2}$ is $\frac{1}{u_{2}}$ .

$e^{\cos (x) \ln (\ln (x))} (\cos (x) (\frac{1}{u_{2}} \frac{d}{d x} [\ln (x)]) + \ln (\ln (x)) \frac{d}{d x} [\cos (x)])$

Step 4.3

Replace all occurrences of $u_{2}$ with $\ln (x)$ .

$e^{\cos (x) \ln (\ln (x))} (\cos (x) (\frac{1}{\ln (x)} \frac{d}{d x} [\ln (x)]) + \ln (\ln (x)) \frac{d}{d x} [\cos (x)])$

Step 5

Combine $\frac{1}{\ln (x)}$ and $\cos (x)$ .

$e^{\cos (x) \ln (\ln (x))} (\frac{\cos (x)}{\ln (x)} \frac{d}{d x} [\ln (x)] + \ln (\ln (x)) \frac{d}{d x} [\cos (x)])$

Step 6

The derivative of $\ln (x)$ with respect to $x$ is $\frac{1}{x}$ .

$e^{\cos (x) \ln (\ln (x))} (\frac{\cos (x)}{\ln (x)} \cdot \frac{1}{x} + \ln (\ln (x)) \frac{d}{d x} [\cos (x)])$

Step 7

Multiply $\frac{\cos (x)}{\ln (x)}$ by $\frac{1}{x}$ .

$e^{\cos (x) \ln (\ln (x))} (\frac{\cos (x)}{\ln (x) x} + \ln (\ln (x)) \frac{d}{d x} [\cos (x)])$

Step 8

The derivative of $\cos (x)$ with respect to $x$ is $- \sin (x)$ .

$e^{\cos (x) \ln (\ln (x))} (\frac{\cos (x)}{\ln (x) x} + \ln (\ln (x)) (- \sin (x)))$

Step 9

Simplify.

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Step 9.1

Apply the distributive property.

$e^{\cos (x) \ln (\ln (x))} \frac{\cos (x)}{\ln (x) x} + e^{\cos (x) \ln (\ln (x))} (\ln (\ln (x)) (- \sin (x)))$

Step 9.2

Combine $e^{\cos (x) \ln (\ln (x))}$ and $\frac{\cos (x)}{\ln (x) x}$ .

$\frac{e^{\cos (x) \ln (\ln (x))} \cos (x)}{\ln (x) x} + e^{\cos (x) \ln (\ln (x))} \ln (\ln (x)) (- \sin (x))$

Step 9.3

Reorder terms.

$- e^{\cos (x) \ln (\ln (x))} \sin (x) \ln (\ln (x)) + \frac{e^{\cos (x) \ln (\ln (x))} \cos (x)}{\ln (x) x}$